With no body markings or colour and a recessive pied type cere he is most likely a dark eyed clear. He doesn't look to have a normal iris ring, so maybe just has a part one or a faint one?
He could be another combination, like a df spangle and recessive pied, I guess. DEC seems just as likely though.
Love the name, kowhai are one of my favourite trees. For those who don't know, kowhai is a native new zealand tree with lovely yellow flowers that the nectar eating birds (especially Tui) love. However, the nectar sometimes ferments in warm weather and you end up with drunk or unconsicous Tui lying about the place.